The invention concerns a method that enables the user of a wireless telephone terminal, intended to be connected to a wireless local network of the IEEE 802.11 type, for example, to establish an emergency connection in a local network, to telephone a rescue center, even if that user has no right of access to the wireless local network that serves the area in which he is situated at the time he needs rescue.
In companies, it is more and more routine to use a wireless mobile telephone connecting, via an IEEE 802.11 type radio link, to a computer and telephone local network belonging to a company. Certain personal digital assistants and certain personal computers also offer this telephone function.
Access to a company local network is generally restricted to certain users who are employees of that company. When the user of this kind of terminal is on the premises of the company that employs him, he has a right of access to the local network, which enables him to telephone in any circumstances. On the other hand, the same user cannot telephone when he is on the premises of another company, because does not have a right of access in the local network of that other company. In particular, he cannot telephone a rescue centre with his usual terminal, unless the latter is a dual mode terminal, i.e. one also enabling access to a public mobile telephone network such as a GSM network.
A method known in public mobile telephone networks, especially GSM type networks, enables the user of a radio-telephone terminal to establish an emergency connection in that network to telephone a rescue centre, even if that user has no right of access to the network which covers the place in which he is situated and even if there is no SIM (Subscriber Identification Module) card in his terminal. This known method consists in authorizing a user to access a mobile service switching centre via a base station and a base station controller even before the terminal has had to satisfy the procedure for authenticating that user. The mobile service switching centre therefore receives the called number and can tell that it is an emergency number. In this case, it does not initiate the authentication procedure but sets up the requested connection.
This method cannot be transposed to an IEEE 802.11 type network because, in that type of network, all current methods of setting up a connection consist in prohibiting a priori the radio access points from setting up a connection between a terminal and the network before the authentication procedure is satisfied, except for a temporary connection with an authentication server, to be able to carry out the authentication procedure.